Process for breaking petroleum emulsions



Patented July 1, 1952 UNITED srarss Mm carries 7 PROCESS .FQR BREAKINGPETROLEUM EMULSIONS Melvin De :Groote, University 'City, Mo.,..assignorxto Petrolite" Corporation, Ltd., Wilmington,.-Del.,

a corporation ,ofDelaware 1 No Drawing. ApplicationSeptember2'5, 1.950,

Seria1N0. 186,682 Y ring watersor brines dispersedin a more or lesspermanent state throughout theoil which constitutes the continuous phaseof the emulsion.

It also provides an economical and rapid process for separatingemulsions which have been prepared under controlled conditions frommineral oil, such as crude oil and relatively soft waters or weakbrines. Controlled .emuls'ification and subsequent demusification underthe-condi- .tions just mentioned are of significant ,value in movingimpurities, particularly inorganic salts. from pipeline oil- 1Demulsification as contemplated in {the present application includes thepreventivesteplo'f-commingling the demulsiflerwith the aqueous:component which would or might :subsequently become either phase of theemulsion in the absence .of such precautionary measure. Similarly, suchdemulsifier may be mixed with the hydrocarbon component. g

The demulsifying .agent employed in .the present process :isa mixedester salt of a monobasic acid and a pol-ybasic acid. "Two moles .of theformerandm'ore specifically, monocarboxy acids are employed whereas onemole .of the latter is employed. The latter is a type in whic'h-two.carboxyl radicals appear and one sulfo radical. The carlooxyl radicalsappears in ester form and the sulfo-radical in salt form.

, .2 propylene ;glyc0l.;a-nd acetic acid, :for -=examnla and one mole101? :a :dicarhoxy c.ompound;such1as maleicannydride; :and ,(c)"reactionbetween'such complete ester and a suitable alkali metalbisulfite such as sodium bisulfite.

Alternately one can esterify the glycol first with "the dicarboxy acidor anhydride and then esterify with a monocarboxy acid, such as aceticacid. 'There is no choice between the two procedures. More specificallythen the present invention is concerned with a process for breakingpetroleum emulsions of the water-in-oil type characterized by subjectingthe emulsion to the action of a demulsifier including hydrophilesynthetic products; said hydrophile synthetic products beingcharacterized by the following formula:

0 H 0 R'ooo osmmfl i-t xocmono00R SOsNa inwhich is the divalent radicalof an unsaturated di- "carboxy acid selected from the class consistingof maleic acid, fumaric acid, and citraconic acid; at is a whole numbervarying from 12 to 80; and R'CO is the acyl radical of a low molalmonocarboxy acid having less than 8 carbon atoms,

and with the proviso that the polypropylene glycol Suchcompounds arederived preferably byire- .35 action between four types of reagents; (a)polypropylene .glycol of a molecular weight sufficient to giveewater-insolubility and kerosene-solubility, generallybein in themolecular weight range of 750 to approximately 3,000; (b a dicarboxycom40 pound selected from the classronsisting of maleic' 7 acid (oranhydride), citraconic acid (or :anhydride),=.and fumaric-acid; (c) alow molal mono j carboxy "acid having less than 8 carbon atoms andpreferably 3 or less; and (d) an alkali metal cation of thepolypropylene glycol mole for'mole with the .low .molal monocarboxyacid, .such 'as acetic acid, propionic acid, lactic "acid, etc, toproduce a fractional ester having .one .free *h ydroxyl radical; (b)esterification between two prior .to esterification be water-insolubleand kerosene-soluble.

In the above formula the alkali metal cation is shown as sodium which isthe cheapest and most .readily available. Needless to say, any otheralkali metal cation, such as potassium, may be employed in the form ofpotassium bisulfite and is included in the hereto attached claims as the.obvious chemical equivalent. Similarly ammonium bisulfite may beemployed instead of sodium or potassium bisulfite. This applies also tothe'bisulfite of various organic bases provided, of course, that suchbases prior to forming a .sulflte are as basic as ammonia and that thesulfite is .wateresoluble. All .these are therebvious functionalequivalent of sodium bisulfit The procedure is illustrated fin Ith'eiollow ng .X- ample. I '1 E A Ew a In a reaction 'flas'k'there wereplaced 9 grams of glacial acetic acid, and "305 grams 'of propyleneglycol 2025 (molal ra tio' o glycol to acid ii-1 moles of the fractionalester obtained from polyalong with one-half arm," of toluene sol-tonicacid. In this instance 1.5 grams were used. There was also added 50 cc.of xylene. Heat was applied and the mixture allowed to reflux for about3 /2 hours. The maximum temperature during the reflux period wasapproximately 145 C. At the end of this time approximately 2 cc. ofwater had been carried over to the phase-separating trap. At the end ofthis period there was still a slight acidity due to the catalyst andalso perhaps a small amount .of uncombined acetic acid. An additional oftoluene sulfonic acid was added along with 8 grams of maleic anhydride.Heat was applied again and the mixture refluxed for 4 hours. The maximumtemperature during the second reflux period, as in the first case, was145 C. The amount of water which distilled over in this instance wasjust a little bit more than one cc. At the end of the reaction periodthere was still a slight acidity due to the presence of the acidcatalyst, possibly some uncombined maleic acid, or anhydride, andpossibly some uncombined acetic acid. A small amount of 30% aqueouscaustic soda was lution was used to neutralize the acidity, then alittle water should be added to dissolve at least part or all of thesodium bisulfite so as to give a saturated solution. The reactionmixture was stirred and heated for three hours. No efiort was made tohave any reflux take place during this stage of the reaction for. theobvious reason that if water were removed and the sodium bisulfite wereanhydrous there would be little or no opportunity for reaction. This wasnecessary also for the reason that sodium bisulfite begins to decomposeat about 100 C. and this reaction obviously must be conducted at asuitable temperature until the sodium bisulfite has combined. Thereafterthe xylene can be distilled over in the usual manner, removing any waterwith it and all the xylene can be removed by distillation, particularlyvacuum distillation. The same procedure was followed in connection witha number of additional samples, all of which are illustrated in thefollowing tables which gives the reactants, amounts employed,temperature of esterification, etc.

Table 1 M. W. of Max. Es- I13x Polyprot.tlloncgart-i Xylene titerigcaggf tigg 0 3 933 (grs.) oxy c1 (gm) (ccm) o (hrs) 725 9 50 145 4% 1,025 155 O..... 9 143 3% 2, 525 375 (10 9 45 143 3% 1, 525 230 Propionic.ll. 5 60 140 3% 2, 025 11. 5 55 141 4 Table 2 Max Max Estenfl- Re- ExDicarboxy Egg cation 33 action NO Reactant (grs.) Temp. flte Temp (h3 1. M51610 Anhydride. 8 145 4 8 30-95 3 2... (1O 8 140 3 /2 8 80-95 3%8 144 3 8 80-95 4% 8 143 3% 8 80-95 4 8 140 4% 8 80- 4 9 149 3 8 80-953% 9 141 4 8 80-95 3% 9 141 4 8 80-95 4% 9 139 4% 8 80-95 3% 9 140 3% 880-95 4 8 144 3% 8 80-95 4 /2 8 143 3% 8 80-95 3% 8 140 3% 8 80-95 4 8141 4 8 80-95 3% 8 14.4 4% 8 80-95 3% 9 139 4% 8 80-95 4% 9 143 3 880-95 3% 9 140 4% 8 80-95 4 9 142 4 8 80-95 3% 9 144 4% 8 80-95 3% addeduntil suflicient had been introduced to neutralize the free sulfonicacid radical and the free carboxyl acid radicals.

After this adjustment, 8 grams of powdered sodium bisulfite were added.Apparently enough water had been added. along with the caustic soda todissolve at least part of the sodium bisulfite so that further additionof Water was not required. Needless to say, if no caustic soda so- 75molecular weight is a fraction,.sometimes a large panacea majorfraction, of :the theoretical molecular weight based theoretically-onthe value one would expect to obtain by treating water or propyleneglycol, for example, with propylene oxi'de. Needless to say, one doesnot obtain a single compound but a propylene glycol of a molecularweight ratio of 750 or 1,000 or 2,000 .as the case may beand reallyrepresents a cogeneri'c mixture whose statistical average molecularweight .:is the one indicated. Reference in the table is, .of

course, to hydroxyl "value molecular weight Jior the-obvious reason thatthis is the 'b'asis'for calculating the amount of reactants'required.

In all instances asmall amountrof1-30% :caustic soda was used as in themore complete description of Example 1. :Also a small :amount of"toluene sulfonic acid, approximately 1% of the used, for instance, atotal of of.].-% or 3/ of 11% based on theamount of glycol, provided,however, that the esterification time is extended somewhat.

One may use any oneof a variety .of monocarboxy acids, such as thosepreviously noted, or higher acids of the aliphatic series, such asbutyric or valeric. The acidsmay be "cyclic as in the case of benzoic,cyclohexanoic and furoic. The acid may have the carbon chain interruptedby an oxygen atom as in the instance of betamethoxy propionic acid. Theacidsmay be hydroxylated as in the case of hydroxyacetic acid or lacticacid. In any event, however, the .acids must be free from any radicalhaving '8 or more uninterrupted carbon atoms in a singlegroup.

One need not prepare the ester Jin 'the'manner described above but mayuse some other conventional procedure as, for example, the use of theacyl chlorideinstead of the acid,-or by alcoholysis involving-methylor-ethylacetate,ethyl or methyl propionate, etc. One'may also start withthe acid itself, such as acetic acid :or propionic acid and subject suchacidto oxypropylation untilthe desired molecular weight is reached.

Theproducts obtained are-comparable to the initial glycol in appearance,etc.,i. e., usually they are an amber color or at least of a slightstraw color, and often somewhat thicker-than-the original *glycol. Thisdescription, of course, applies to materials after the removal of thesolvent, i. e., the xylene. For use as 'demulsifiers'there is no need toremove the xylene and -it may remain behind. Obviously other liquidsthan xylene may be used in esterification procedure. However, if theboiling point is any hi'g'h'er than xylene there is danger thatdecomposition may take place unless the amount of 'sulfonic acid isreduced. Other-catalystssuch asasmallaamount of dry hydrochloric acidcan be used but 'it appears less desirable thanthe sul'fonic'acid.Needless to say, thecaustic soda solutionusedpeutralizes the -sulfomcacid catalyst present.

The equipment-used' in -esterification procedure is a resin pot of the'kind describedi-n'U. SsPaterit No. 2,499,370, dated March 7, 1950, to De'Groote and Keiser. hny conventional equipment can be used, either-on asmall scale, pilot plantscalepr larger scale.

In the various examples preceding only one glycol has been used in thesecases. Actually there is no reason whylone may'not use two :differentglycols, for instance, an equimolarmixture of two glycols, one forexample :having a molecular weight of 2000 and the other 3000, :or onehaving a molecular weight of 1500 and the other 2500. Actually theseglycols .arecogenericmixtures, atea'ch selected :molecular weight. 'Ifone does make :a mixture act the kind here :described actually threetypes of compounds will appear;

.one type in "which both marboxylfradicalsof the polycarboxy acid are:joined'fwith the higher :gly- "001, one type where both carbox-yls arejoined with the lower molecular weight glycol, .and one type where one'carb'oxyl v.is united to a higher molecularweight glycol, and theanther .one .to :a

lower molecular weight ig'lycol.

Other variations are obviously possible by us-- ing difierentmonocarboxya'cids. For example,

8 or more uninterruptedcarbon atoms, and (b the compounds are notparticularlyefiective as surface-active agents .in the ordinary sensedue either to the large molecular size or the "absence of a hydrophoberadical 'of the kind previously referred to, or for some other reasonwhich is obscure. The chemical compounds herein employed as'demulsifiers .have molecular weights varying from more ithan21000 up toseveral thousands, for instance, 5000, 16000, or7000, and yet containonly one sulfo radical. Utility of such compounds for industrial uses israther unusual. They are not effective emulsifying agents, but arevaluable as an additive or a promoter of emulsions. These compounds alsohave hydrotropic property and serve as common solvents in thepreparation of micellar solutions. It :is to be noted that they are freefrom terminal .carbox-yl radicals and thus difier from reagentsobtained, for example, by treating one mole of a high molalpolypropylene glycol with .2 moles of ,adicarboxy acid. It is probablethese reagents, due to their peculiar structure and their peculiarsolubility characteristics, willfind utility in other fields ofapplication now unknown.

Conventional demulsi'i'ying agents employed in the treatment of oilfield emulsions are used as such, or after dilution with-any suitablesolvent, such as -wa'ter, petroleum hydrocarbons, such as benzene,toluene, xylene, tar acid oil, cresol, 'anthracene oil,-etc. Alcohols,particularly aliphatic alcohols-such as methyl "alcohol, ethyl alcohol,denatured alcohol, propyl alcohol, butyl alcohol, hexyl alcohol, :o'ctylalcohol, etc., may be employed asdiluents. Miscellaneoussolvents such aspine oil, carbon tetrachloride, sulfur dioxide extractobtainedin'therefining o'f petroleum, etc., may be employed as .diluents. :Siniilarly,.the material or materials employed .as the demulsifying agent of myprocess may be .admixed with-one or. more of the:solvents-custom arilyused in connection with conventional demulsifying agents. Moreover,.said ,material or materials :may be used :alone :or admixture withother suitable well-known classes of demulsifying agents.

It is well known that conventional demulsifying agents may be ,used in awater-soluble form, or in an oil-soluble form, or in a form exhibitingboth oiland water-solubility. Sometimes they may be used in .a formwhich exhibits relatively limited oil-solubility. However, since suchreagents are frequently used in a ratio of 1 to 10,000 or 1 to 20,000,or 1 to 30,000, or even 1 to 40,000, or 1 to 50,000 as in desaltingpractice, such an apparent insolubility in oil and water is notsignificant because said reagents undoubtedly have solubility withinsuch concentrations. This same fact is true in regard to the material ormaterials employed as the demulsifying agent of my process.

In practicing my process for resolving petroleum emulsions of thewater-in-oil type, a treating agent or demulsifying agent of the kindabove described is brought into contact with or caused to act upon theemulsion to be treated, in any of the various apparatus now generallyused to resolve or break petroleum emulsions with a chemical reagent,the above procedure being used alone or in combination with otherdemulsifying procedure, such as the electrical dehydration process.

One type of procedure is to accumulate a volume of emulsified oil in atank and conduct a batch treatment type of demulsification procedure torecover clean oil. In this procedure the emulsion is admixed with thedemulsifier, for example by agitating the tank of emulsion and slowlydripping demulsifier into the emulsion. In some cases mixing is achievedby heating the emulsion while dripping in the demulsifier, dependingupon the convection currents in the emulsion to produce satisfactoryadmixture. In a third modification of this type of treatment, acirculating pump withdraws emulsion from, c. g., the bottom of the tank,and reintroduces it into the top of the tank, the demulsifier beingadded, for example, at the suction side of said circulating pump.

In a second type of treating procedure, the demulsifier is introducedinto the well fluids at the well-head or at some point between thewellhead and the final oil storage tank, by means of an adjustableproportioning mechanism or proportioning pump. Ordinarily the fiow offluids through the subsequent lines and fittings suffices to produce thedesired degree of mixing of demulsifier and emulsion, although in someinstances additional mixing devices may be introduced into the flowsystem. In this general procedure, the system may include variousmechanical devices for withdrawing free water, separating entrainedwater, or accomplishing quiescent settling of the chemicalized emulsion.Heating devices may likewise be incorporated in any of the treatingprocedures described herein.

A third type of application (down-the-hole) of demulsifier to emulsionis to introduce the demulsifier either periodically or continuously indiluted or undiluted form into the well and to allow it to come to thesurface with the well fluids, and then to flow the chemicalized emulsionthrough any'desirable surface equipment, such as employed in the othertreating procedures. This particular type of application is decidedlyuseful when the demulsi-fier'is used in connection with acidification ofcalcareous oilbearing strata, especially if suspended in or dissolved inthe acid employed for acidification.

In all cases, it will be apparent from the foregoing description, thebroad process consists simply in introducing a relatively smallproportion of demulsifier into a relatively large proportion ofemulsion, admixing the chemical and emulsion either through natural flowor through special apparatus, with or without the application of heat,and allowing the mixture to stand quiescent until the undesirable watercontent of the emulsion separates and settles from the mass.

The following is a typical installation.

A reservoir to hold the demulsifier of the kind described (diluted orundiluted) is placed at the well-head where the efliuent liquids leavethe well. This reservoir or container, which may vary from 5 gallons to50 gallons for convenience, is connected to a proportioning pump whichinjects the demulsifier drop-wise into the fluids leaving the well. Suchchemicalized fiuids pass through the flowline into a settling tank. Thesettling tank consists of a tank of any convenient size, for instance,one which will hold amounts of fiuid produced in 4 to 24 hours (500barrels to 2000 barrels capacity), and in which there is a perpendicularconduit from the top of the tank to almost the very bottom so as topermit the incoming fluids to pass from the top of the settling tank tothe bottom, so that such incoming fluids do not disturb Stratificationwhich takes place during the course of demulsification. The settlingtank has two outlets, one being below the water level to drain off thewater resulting from demulsification or accompanying the emulsion asfree water, the other being an oil outlet at the top to permit thepassage of dehydrated oil to a second tank, being a storage tank, whichholds pipeline or dehydrated oil. If desired, the conduit or pipe whichserves to carry the fluids from the well to the settling tank mayinclude a section of pipe with bafiles to serve as a mixer, to insurethorough distribution of the demulsifier throughout the fluids, or aheater for raising the temperature of the fluids to some convenienttemperature, for instance, to F., or both heater and mixer.

' Demulsification procedure is started by simply setting the pump so asto feed a comparatively large ratio of demulsifier, for instance,1:5,000. As soon as a complete break or satisfactory demulsification isobtained, the pump is regulated until experience shows that the amountof demulsifier being added is just sufiicient to produce clean ordehydrated oil. The amount being fed at such stage is usually 1:10,000,1:15,000, 1:20,- 000, or the like.

In many instances the products herein specified as demulsifiers can beconveniently used without dilution. I However, as previously noted, theymay be diluted as desired with any suitable solvent. For instancebymixing 75 parts of such derivative, for example, the product of Example1 with 15 parts by weight of xylene and 10 parts by weight of isopropylalcohol, an excellent demulsifier is obtained. Selection of the solventwill vary, depending upon the solubility characteristics of theoxyalkylated product, and of course will be dictated in part by economicconsiderations, i. e., cost.

As noted above, the products herein described may be used not only indiluted form, but also may be used admixed with some other chemicaldemulsifier. v v

1 Having thus described my invention "what I claim as new and desire tosecure by Letters Patent, is:

1. A process for breaking petroleum emulsions of the water-in-oil typecharacterized by sub jecting the emulsion to the action of a demulsifierincluding hydrophile synthetic products; said hydrophile syntheticproducts being characterized by the following formula:

S OaNa in which O t l R t is the divalent radical of an unsaturateddicarboxy acid selected from the class consisting of maleic acid,fumaric acid, and citraconic acid; n is a whole number varying from 12to 80; and RCO is the acyl radical of a low molal monocarboxy acidhaving less than 8 carbon atoms, and with the proviso that thecorresponding polypropylene glycol of the formula HO (CBHGO) 11H bewater-insoluble and kerosene-soluble.

2. The process of claim 1 wherein the dicarboxy acid is maleic acid.

3. The process of claim 1 wherein the dicarboxy acid is maleic acid andthe value of n corresponds to a polypropylene glycol of approximately700 molecular weight.

4. The process of claim 1 wherein the dicarboxy acid is maleic acid andthe value of n corresponds to a polypropylene glycol of approximately1000 molecular weight.

5. The process of claim 1 wherein the dicarboxy acid is maleic acid andthe value of n corresponds to a polypropylene glycol of approximately1500 REFERENCES CITED 'The following references are of record in thefile of this patent:

UNITED STATES PATENTS Number Name Date 2,072,085 De Groote et a1 Mar. 2,1937 2,184,794 De Groote et al. Dec. 26, 1939 2,301,609 Bonnet Nov. 10,1942 2,305,067 De Groote Dec. 15, 1942 2,315,375 Nawiasky et a1. Mar.30, 1943 2,353,694 De Groote et a1. July 18, 1944 2,514,399 Kirkpatricket al. July 11, 1950

1. A PROCESS FOR BREAKING PETROLEUM EMULSIONS OF THE WATER-IN-OIL TYPECHARACTERIZED BY SUBJECTING THE EMULSION TO THE ACTION OF A DEMULSIFIERINCLUDING HYDROPHILE SYNTHETIC PRODUCTS; SAID HYDROPHILE SYNTHETICPRODUCTS BEING CHARACTERIZED BY THE FOLLOWING FORMULA: